Antisolvent-Precipitated Asiatic Acid Particles as Dual-Function Stabilizers for Water-in-Oil Pickering Emulsions

Pickering emulsions stabilized by edible or natural particles have broad applications in food and pharmaceutical fields, yet suitable stabilizers for water-in-oil (W/O) systems remain far less abundant than those for oil-in-water (O/W) emulsions. Asiatic acid (AA) is a pentacyclic triterpenoid with diverse physiological activities and amphiphilic characteristics; however, its interfacial properties remain poorly understood. In this study, AA was modified through antisolvent precipitation (Anti-AA) to generate self-stabilized W/O emulsions. The antisolvent treatment effectively reduced particle size, induced rod-like morphology, and enhanced surface wettability. Increasing Anti-AA concentration (c = 0.5–3 wt%) significantly improved emulsion stability. Anti-AA demonstrated superior storage, thermal, and freeze-thaw stability compared to native AA even at low concentrations. AA-stabilized Pickering emulsions exhibited high fluidity with dominant viscous behavior, and their viscoelastic properties were enhanced with the increasing AA concentration. Notably, AA substantially inhibited lipid oxidation. Confocal laser scanning microscopy (CLSM) analysis revealed that AA crystals formed an interfacial physical barrier, effectively suppressing droplet coalescence. This research demonstrates an effective strategy for developing stable natural W/O emulsions while expanding bioactive applications in functional foods and pharmaceutical formulations. Graphical